Apparatus for a carriage traveling along a roof structure

ABSTRACT

An apparatus is movable along a roof structure having a plurality of elongated purlins defining longitudinal axes. The apparatus includes a carriage movable along the length of the purlins. The carriage extends across the purlins. A plurality of support members are mounted on the carriage and engage with the purlins. Each of the support members includes a flange which abuts a purlin to prevent the purlin from twisting about its longitudinal axis.

TECHNICAL FIELD

[0001] This invention relates to the construction of an insulated metal roof structure for use in commercial and industrial buildings.

BACKGROUND OF THE INVENTION

[0002] Metal roof structures typically comprise a series of parallel rafter beams extending across the building in one direction and purlin beams parallel to each other mounted on top of the rafters extending in a direction normal to the rafters. The purlins are spaced apart from one another in a parallel arrangement which define a generally horizontal or sloped plane. The purlins are commonly attached to the rafter beams by threaded fasteners. The purlins typically have a Z-shaped cross-section including generally horizontal upper and lower portions joined together by a generally vertical portion. The Z-shaped purlins are typically formed by bending an elongated flat sheet of metal at generally right angles to form the vertical and lower portions. The lateral edges of the horizontal portions may also be slightly bent at an inwardly extending angle. The purlins can be joined together by lateral support bracing or straps extending between adjacent purlins to meet load structural design criteria of the roof structure. This is often done for roof structures which need extra support, such as for buildings where snow is likely to collect on the roof structure. However, the addition of the bracing is time consuming and costly.

[0003] Insulation material in long sheets is commonly placed in the area between purlins. The sheets of insulation material can be laid along the length of the purlins or across the purlins in a direction normal to the purlins. Hard roofing material such as metal decking is then attached on top of the purlins over the insulation material. The hard roofing material is attached to the upper horizontal portions of the purlins by threaded fasteners or clips. Because the hard roofing material comes in long sheets and the roofs generally have two sloped sections, it is customary to construct the roof along the width of the sloped section and then proceed along the length of the structure from one end to the other. The workers stand on the previously laid section of roof to construct the next section.

[0004] The insulation material must be supported between the purlins, and various methods of support have been used. Mounting straps or wire mesh that are attached to the purlins by forming a lattice have been used. This is referred to as banding. A sheet, typically made of vinyl and acting as a vapor barrier, is then rolled onto the lattice, and insulation material is placed between adjacent purlins and over the sheet. If the installation of the lattice is done from underneath the roof structure, scaffolding or lifting equipment is required.

[0005] Some systems dispense with the lattice and use the sheet itself to support the insulation material. The support sheet is draped from the adjacent purlins and the insulation material is placed on top of the support sheet. A carriage is used to aid in the dispensing of the support sheet. The carriage is positioned on top of the purlins and travels the length of the purlins during the roof construction. A roll of the support sheet material is mounted on the carriage and the support sheet is dispensed from the roll and placed on top of the purlins. As the carriage travels the length of the purlins the support sheet is draped across the purlins.

[0006] A carriage in the form of a movable platform can also be used for building a roof structure that does not use a draped support sheet for supporting insulation material. For example, the roof structure can be formed by fastening deck sheets on top of the purlins and then applying insulation foam board and a waterproof membrane above the deck sheets. The carriage can support workers thereupon and also help protect workers from falling over the leading edge of the roof. The carriage often includes a guardrail to further protect the workers from falling over the leading edge of the roof structure.

[0007] Although the method of using a carriage has been found to be very successful in applying insulation material, under certain circumstances the weight of the roof structure itself, the weight of the workers thereon, or the weight of the carriage if used to construct the roof structure can deform the purlins by bending and/or twisting. An example of a purlin which is twisted is shown in FIG. 4 at phantom lines 102. Due to the Z-shaped cross section of the purlins, the purlins naturally tend to twist in one rotational direction, i.e., counter-clockwise as viewing the Z-shape cross section. The twisting effect usually occurs in the region of the purlin located farthest from the fastening point with the rafter beams. Thus, the twisting generally occurs in a middle region of the purlin between the points of attachment to the rafter beams. The twisting effect of the purlins can cause problems with the fastening of the hard roofing material or deck sheets by threaded fasteners or clips. The hard roofing material should be fastened to the upper horizontal portions of the purlins such that the upper horizontal portions of the purlins are oriented in a horizontal manner, and not slanted due to the twisting effect.

[0008] The purlins may also bend or deform from their original shape to a deformed shape. For example, a Z-shaped purlin generally has a planar upper horizontal portion which is perpendicular to a planar vertical web which is perpendicular to a planar lower horizontal portion when the Z-shaped purlin is in an original position. The Z-shaped purlin may be deformed such that the angle between the upper horizontal portion and the vertical web and the angle between the vertical web and the lower horizontal portion are each greater than 90 degrees such that the vertical web is no longer oriented in a vertical plane. Thus, the purlin has a slanted Z-shaped cross-section. This deformation of the purlins is also undesirable due to complications which can arise when constructing the roof structure as described above with respect to the twisting of the purlins.

[0009] Although the carriages often have guide wheels for guiding and directing the carriage as the carriage travels along the length of the purlins, the guides generally do not prevent the purlins from twisting. An example of such a guide is disclosed in U.S. Pat. No. 5,653,083, which discloses the use of one or two vertically oriented wheels positioned on one or both sides of the purlin. Although the guides are suitable for guiding the carriage along the length of the purlins, the cylindrical vertical face of the wheel does not always prevent the purlin from twisting. Another example of a guide roller is disclosed in U.S. Pat. No. 5,911,385 which uses a support roller having frustoconical portions to help track the carriage along the upper portions of the purlins. However, the frustoconical portions do not completely prevent the purlin from twisting or moving laterally since the upper portion of the purlins can simply slide up along the frustoconical portion of the guide rollers.

[0010] To combat the problem of the twisting purlins, it has been known to install permanent bracing between or straps over adjacent purlins to provide lateral support. However, this permanent bracing is costly and time consuming to install. It has also been known to temporarily position beams, such as wooden planks, between the purlins to temporarily brace the purlins prior to the attachment of the hard roofing material. Once the hard roofing material is fastened to the upper portions of the purlins, the temporary bracing can be removed since that portion of the purlin attached to the hard roofing material is supported by the attachment. However, the use of temporary bracing is time consuming, and it can be very difficult to install and remove the bracing since the bracing is installed under the hard roofing material.

[0011] It would be desirable to have a system for building a roof structure with a carriage that provides for an insulation support system which is convenient and efficient to construct.

SUMMARY OF THE INVENTION

[0012] The above objects as well as other objects not specifically enumerated are achieved by an apparatus which is movable along a roof structure having a plurality of elongated purlins defining longitudinal axes which are spaced apart from one another in a parallel arrangement. Preferably, the purlins have a generally Z-shaped cross-section including a generally horizontally extending upper portion, a generally horizontally extending lower portion, and a vertically extending web disposed between the upper portion and the lower portion. The apparatus includes a carriage movable along the length of the purlins. The carriage extends across the purlins. A plurality of support members are mounted on the carriage and engage with the purlins. Preferably, there is at least one support member for every one of the plurality of purlins. Each of the support members includes a flange which abuts the upper portion of a purlin to prevent the purlin from twisting about the longitudinal axis of the corresponding purlin. Preferably, the support member includes a mounting member adapted to be attached to the carriage and a roller rotatably attached to the mounting member and adapted to rotatably engage the purlin as the carriage moves along the length of the purlins.

[0013] Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]FIG. 1 is a schematic elevational side view of a carriage including a puller assembly and support members, in accordance with the present invention.

[0015]FIG. 2 is a schematic sectional view taken along Lines 2-2 of FIG. 1 illustrating a completed section of the insulated roof structure.

[0016]FIG. 3 is a schematic top plan view of a plurality of carriage sections on top of the roof structure.

[0017]FIG. 4 is an enlarged view of a support member of the invention shown engaged with a purlin.

[0018]FIG. 5 is a schematic elevational side view of a platform carriage including support members, in accordance with the present invention.

[0019]FIG. 6 is an enlarged view of an alternate embodiment of a support member shown engaged with a bar joist.

DETAILED DESCRIPTION AND PREFERRED EMBODIMENTS OF THE INVENTION

[0020] Referring to FIGS. 1 and 2, there is illustrated a partially completed building roof structure, indicated generally at 10. The roof structure is supported by a building framework which includes main rafter beams 12 positioned parallel to each other. A plurality of purlins 18, spaced apart and arranged parallel to each other, is fastened on top of the rafters in a direction normal to the rafters. The building framework may have two sloped sections (not shown) which are joined together to form a peak. The spacing of the rafter beams is typically within the range of from about 25 to about 30 feet (7.6 to about 9.1 meters) on centers. The spacing of the purlins 18 is typically about 5 feet (1.52 m) on centers.

[0021] As best shown in FIG. 4, the purlins 18 typically have a generally Z-shaped cross-section, and include a generally horizontally extending planar upper portion 20, a generally vertically extending planar web 22, and a generally horizontally extending planar lower portion 24. The purlins 18 may also be formed with an upper flange 21 extending at an angle relative to the edge of the upper portion 20. Similarly, a lower flange 23 extends at an angle relative to the edge of the lower portion 24. The Z-shaped purlins 18 can be formed by bending an elongated flat sheet of metal at appropriate angles to define the portions 20, 22, and 24 and the flanges 21 and 23. Although the present invention is described and shown being used with Z-shaped purlins 18, it should be understood that the present invention can be used with any suitable beam structures, such as bar joists or trusses, which may have a tendency to twist. Thus, the use of the term “purlins” in this specification and claims may include not only traditional purlins, but also joists, trusses, and other suitable structural members for supporting the roof structure.

[0022] The roof structure is preferably constructed by use of a carriage, indicated generally at 26, which rides on the upper portion 20 of the purlins 18 and travels along the length of the purlins 18 in a downstream direction, represented by an arrow 28, as shown in FIG. 1. Preferably, the carriage has rollers 30, rotatably mounted on the carriage, which roll along the upper portions of the purlins to support the carriage on the roof structure. As will be discussed in detail below, the carriage 26 also includes a plurality of guide or temporary support members 100 which help prevent the purlins from twisting and/or bending about their longitudinal axis. The purlin deformation, either from twisting or bending can be caused by the weight of the roof structure itself, the weight of the workers thereon, or the weight of the carriage if used to construct the roof structure due to the weight of the carriage 26. The support member 100 can also function similar to the rollers 30 by rolling along the upper portions of the purlins to support the carriage on the roof structure. Of course, the carriage can include any suitable combination of rollers 30 and/or support members 100 to support the carriage on the roof structure. For example, as shown in FIG. 1, the carriage 26 includes rollers 30 mounted on a front portion thereof, and support members mounted on a rear portion thereof.

[0023] As the carriage is moved, a support sheet 32 is payed out from rolls 34 and 42, as will be discussed below. The support sheet is draped on top of adjacent purlins so that the longitudinal edges of the support sheet depend from the upper portion of the purlins, as shown in FIG. 2. The support sheet supports a layer of insulation material 36 which is placed on top of the support sheet between the adjacent purlins. The insulation material is typically dispensed from a roll 38 but can be applied by any suitable manner, such as by applying elongated insulation batts on top of the support sheet. Alternatively, a layer of insulation may be placed laterally across the purlins. After the insulation material has been placed on the support sheet, long sheets of hard roofing material 40, such as metal roof decking, are then attached to the upper portion 20 of the purlins 18 over the support sheet and insulation. The hard roofing material 40 can be fastened to the purlins in any suitable manner, such as by threaded fasteners or clips. The attachment of the hard roofing material presses down on the edges of the support sheet which are sandwiched between the upper portion 20 of the purlins and the hard roofing material 40, so that the support sheet supports the insulation between the purlins.

[0024] Because the hard roofing material comes in long sheets, typically 30 to 35 feet (9.1 to 10.7 m), and the roofs generally have two sloped roof sides, it is customary to construct a first section of the roof structure along the width of the sloped roof side and then proceed along the length of the structure from one end to the other. The workers stand on the previously attached first section of the roof structure to assemble the next section of roof. The carriage travels along the length of the purlins and is moved by the workers as each new section of roof is assembled.

[0025] As best shown in FIG. 3, the carriage is preferably comprised of a plurality of carriage sections 26 a which are joined together. The carriage sections are joined at their respective ends 90 so that they are generally in alignment with each other, as shown in FIG. 3. The carriage sections can be joined together by any suitable manner, such as by being clamped or bolted together. Preferably, the carriage spans the entire width of the sloped section of the roof, but it can be any length up to the width of the roof itself. Note that in FIG. 3, the support sheets and insulation material are removed for clarity.

[0026] To construct the roof structure 10, the carriage 26 is propelled across the purlins in the downstream direction 28. As the carriage moves along the length of the purlins, the ends of the support sheets 32 are draped across the upper portion of adjacent purlins. Preferably, the total width of the support sheet is wider than the distance between the purlins. Adjacent support sheet rolls may be positioned in a staggered and offset manner such that they are not co-linear with each other. Preferably, a carriage section 26 a covers two purlin spans, as shown in FIG. 3. Each carriage section may have a leading roll 34 and a trailing roll 42 of insulation support sheet, one roll for each of two adjacent purlin spans, as shown in FIG. 1. The edge of the support sheet from the trailing roll 42 will be draped on top of the edge of the support sheet from the leading roll 34 as the carriage moves in the downstream direction. Multiple identical carriage sections having a leading and trailing roll can, therefore, be joined together, with every roll being staggered from an adjacent roll.

[0027] The carriage 26 can be any suitable apparatus which moves along the top of the purlins. As seen from FIG. 1, the carriage preferably includes safety handrails 44 and a deck 46 for the workers to stand on while operating or moving the carriage. The rollers 30 and support members 100 are mounted from the deck 46 of the carriage. Preferably, the carriage is equipped with a combination of two rollers and/or support members 100 (front and rear) for each purlin, as shown in FIG. 1. The carriage also includes a framework 48 for mounting the rolls 34 and 42. Mounted on the framework are turning bars 50 which extend laterally across associated support sheets and are positioned slightly above the upper portions 20 of the purlins 18 so as to direct the support sheet to a generally horizontal position.

[0028] Attached to the carriage is an optional plate 52 which extends from the carriage in an upstream direction opposite the downstream direction 28. The plate supports the payed out portion of the support sheet and insulation material so that the support sheet does not drape downwardly, thereby pulling the longitudinal edges of the support sheet off the upper portion of the purlins. If sufficiently built, the plate can be used for fall protection for the workers to prevent them from falling off the leading edge of the previously completed section of roof. The plate can be attached to the carriage by any suitable means. The plate follows the carriage as the carriage moves along the length of the purlins. Preferably, the plate has wheels 54 which also support the plate by rolling along the upper portion 20 of the purlins 18. However, it is not required that the payed out support sheet be supported by the plate. The carriage could be modified so that the support sheet is payed out in such a manner that the support sheet is underneath the plate. If desired, the roll 38 of insulation material 36 could be positioned on the plate 52 above the support sheet.

[0029] The space between the vertical webs 22 of adjacent purlins 18 generally defines an insulation cavity 58, as shown in FIG. 2. The insulation cavity has a generally rectangular cross-sectional shape. The support sheet supports the insulation material in the insulation cavity. The support sheet can also be used as a vapor barrier and/or for aesthetic purposes. The support sheet can be of any suitable material for the stated purposes, such as vinyl or foil faced paper.

[0030] The carriage 26 is propelled or advanced along the length of the purlins in the downstream direction 28 by a plurality of puller assemblies 60. The puller assembly 60 can be any suitable apparatus which is attached to or mounted on a carriage section and provides means for moving the carriage along. Examples of suitable puller assemblies are disclosed in U.S. Pat. Nos. 6,195,958 and 6,041,568 which are incorporated by reference herein. The puller assembly can include a motor 62 for driving a drive mechanism 64 which rotates a wheel 66 frictionally engaging the purlin. The rotation of the wheel causes the puller assembly and the carriage to move along the length of the purlins. The puller assembly 60 can be attached to the carriage section by any suitable manner, such as by a cable 68, or can be mounted directly on the carriage section. Another example of a puller assembly is the use of one or more power winches, wherein one end of a cable is operatively connected to the carriage and the other end of the cable is fixed, such as attached to a portion of the roof structure.

[0031] When a relatively large number of carriage sections are used, multiple numbers of puller assemblies are used to move the carriage. When a plurality of puller assemblies is used, it is desirable to simultaneously control the plurality of puller assemblies so that the carriage sections will move in unison along the length of the purlins. The puller assemblies can be controlled by a single electrical controller 70, such as that disclosed in U.S. Pat. No. 6,101,782 which is incorporated by reference herein. The controller is preferably mounted on one of the carriage sections, such as for example, on the handrail 44. The controller is electrically connected with the puller assemblies via cords 74. The controller is connected to a source of power 76, such as a generator or battery. Preferably, the controller controls the puller assemblies by directing electrical power from a single source to the plurality of puller assemblies. Of course, multiple power sources can be used. Each puller assembly can also be provided with its own source of power, wherein the controller controls every source of power.

[0032] As stated above, the carriage 26 preferably includes a plurality of support members 100 to help prevent the purlins 18 from twisting about their longitudinal axis due to the weight of the carriage 26. The Z-shaped purlins 18 have a natural tendency to twist about a longitudinal axis X, as shown in FIG. 4, to a deformed state as represented by phantom lines 102 in FIG. 4. Due to the Z-shaped cross section of the purlins 18, the purlins 18 tend to twist in one rotational direction, i.e., counter-clockwise as viewing the Z-shape cross section. This twisting effect usually occurs in the central region of the purlins 18 between the rafter beams 12 since the purlins 18 are supported and fastened to the rafter beams 12 at their intersection. The twisting effect of the purlins can cause problems with the proper fastening of the hard roofing material 40 onto the upper portions 20 of the purlins 18. The hard roofing material 40 should be fastened to the upper horizontal portions of the purlins such that the upper horizontal portions of the purlins are oriented in a horizontal manner, and not slanted due to the twisting effect. If threaded fasteners (not shown) are used to fasten the hard roofing material 40 to the purlins 18, a purlin 18 which is twisted, like the purlin 102 in FIG. 4, may not be properly mated with the threaded fastener due to the vertical gap between the hard roofing material 40 and the upper portion of the purlin. Alternatively, if clips (not shown) are used to fasten the hard roofing material 40 to the purlins 18, it may be impossible for the clip to perform to its designed function if the purlin is sufficiently twisted out of a normal position. Thus, in a preferred embodiment of the invention, the carriage 26 includes support members 100 at every purlin 18 which is prone to twisting, as will be discussed below.

[0033] Referring to FIG. 4, there is illustrated a preferred embodiment of a support member, indicated generally at 100. The support member 100 includes a mounting assembly, indicated generally at 104, for mounting the support member 100 to the carriage 26. The mounting assembly 104 preferably releasably mounts the support member 100 to the carriage 26. The mounting assembly 104 can be attached to any suitable portion of the carriage 26, such as a bracket 106 extending from the edge of the deck 46. The mounting assembly 104 can be any suitable structure. As shown in FIG. 4, the mounting assembly 104 includes a plate 108 fixed to a pair of C-shaped members 110. The C-shaped members 110 include upper legs 112 and lower legs 114. Each upper leg 112 of the pair of C-shaped members 110 preferably includes a threaded bore 116 for receiving threaded bolts 118. The mounting assembly 104 clamps to the angle bracket 106 of the carriage 26 by sandwiching the angle bracket 106 between the plate 108 and the ends of the bolts 118.

[0034] The support member 100 preferably includes a cylindrical rod 120 extending downwardly from the plate 108. Preferably, the rod 120 extends downwardly at an angle, such as 45 degrees relative to a plane defined by the spaced apart purlins, along an axis A. The support member 100 further includes a roller, indicated generally at 122, which is rotatably mounted on an end 132 of the rod 120. The roller 122 rotates about the axis A. The axis A is preferably between 30 and 60 degrees relative to the plane defined by the purlins, and more preferably at 45 degrees. The roller 122 includes a cylindrically shaped main portion 124. The roller 122 further includes a relatively thin cylindrical disc or outer flange 126 having a larger diameter than the main portion such that the flange 126 extends radially outwardly from the main portion 124. The flange 126 preferably includes a frustoconically shaped beveled lip or edge 127. The roller preferably includes a frustoconically shaped wheel portion 128. The roller 122 can be secured to the end 132 of the rod 120 by a threaded bolt 136. Of course, the roller 122 can be secured to the end 132 of the rod 120 by any suitable manner. Preferably a bushing 130 is disposed between an outer cylindrical surface of the bolt 136 and a cylindrical inner bore 134 formed in the main portion 124 to provide reduced rotational friction between the rod 120 and roller 122. The main portion 124, the frustoconically shaped wheel portion 128, and the flange 126 can be fixed relative to one another or separately mounted. Alternatively, the main portion 124, the frustoconically shaped wheel portion 128, and the flange 126 can be integrally formed as a single structure.

[0035] As shown in FIGS. 4, the roller 122 generally conforms to the left side of the upper portion 20 of the purlin 18 to trap or confine the upper portion 20 and flange 21 to prevent the purlin 18 from twisting or rotating to the position 102. The wheel portion 128 has an outer frustoconical surface 140 which abuts and rolls along the upper surface of the upper portion 20 of the purlin 18. The wheel portion 128 provides support for the carriage on the roof structure and permits the carriage 26 to roll along the upper portions of the purlins. The main portion 124 has an outer cylindrical surface 142 which abuts and rolls along the upper surface of the upper flange 21. Note that the angle of the axis A of the rod 120 preferably corresponds to the angle of the upper flange 21, which are commonly at 45 degrees relative to the horizontal. Thus, the outer cylindrical surface 142 of the main portion 124 is flush against an upper surface of the flange 21. Similarly, the outer frustoconical surface 140 of the wheel portion 128 is flush with the upper surface of the upper portion 20 of the purlin 18. The outer flange 126 includes a surface 144 defining a plane which functions as a stop to prevent movement of a free edge 146 of the flange 21 of the purlin 18 in a counter-clockwise direction, as viewing FIG. 4. Preferably, the flange 21 abuts the surface 144 of the outer flange 126 at a perpendicular orientation to reduce the likelihood of the edge 146 slipping past the outer flange 126.

[0036] The beveled edge 127 of the flange 126 functions as a ramped member such that the flange 126 can slide and roll easily along the purlins without getting caught on any obstructions or purlin joint seams in which two purlins are connected together. It should also be understood that the roller 122 can be used without the flange 126 and essentially just the main portion 124 and wheel portion 128.

[0037] In operation of the carriage 26, it is preferred that substantially every purlin prone to deformation, such as by bending or by twisting about its longitudinal axis, be prevented from deformation by placement of a support member 100 adjacent thereto or engaged with a puller assembly 60. In a typical roof structure, every purlin having a Z-shaped cross-section is generally prone to twisting. However, some roofing beams such as eave struts (not shown) along the edge of the roof structure may have a C-shape cross-section which may not be prone to twisting due to its cross-sectional shape and/or its metal gauge thickness. Therefore, a support member 100 would not be needed for the eave strut. Generally, a support member 100 is not needed for the purlins having puller assemblies 60 mounted thereon since the puller assembly is preferably configured such that the purlin upon which it is mounted on is prevented from twisting due to the contact of the rollers 66 of the puller assembly 60. Thus, the puller assembly inherently has a support member with a flange therein which abuts the corresponding purlin to prevent the corresponding purlin from twisting about the longitudinal axis of the corresponding purlin. However, a support member 100 may still be used and engaged with the purlin associated with puller assembly to function as a support for the carriage, in a similar manner as the rollers 30. As an example of a suitable carriage configuration, there is illustrated in FIG. 3, a portion of a carriage 26 having a plurality of carriage sections 26 a joined together. For the illustrated portion of the carriage 26, there are two puller assemblies 60 with seven purlins 18 therebetween. A support member 100 is used for each purlin 18 not having a puller assembly associated therewith. Thus, substantially every purlin 18 has either a puller assembly 100 or a support member associated therewith. It should be understood that the phrase “substantially every purlin” does not require that every purlin of the entire roof structure be engaged with a support member.

[0038] Another advantage of the support member 100 is that the flange 126 of the support member 100 helps maintain the carriage 26 on a roof structure which is sloped or angled with respect to the horizontal. The slope of the roof structure can be defined as the slope of the plane defined by the parallel arrangement of the plurality of spaced apart purlins. As viewing FIG. 4, the purlins 18 are oriented on a sloped roof such that the upper portion 20 extends upward towards the peak. Thus, the roof structure would slope down to the right as viewing FIG. 4. This is the preferred purlin arrangement since the generally 90 degree bends between the portions 20, 22, and 24 of the Z-shaped purlins 18 are less likely to bend inwardly than outwardly. If the roof structure is sloped in a down to the right direction as viewing FIG. 4, the carriage 26 has a tendency to slide to the right. However, the surface 144 of the flange 126 functions as a stop preventing the carriage from moving with respect to the purlins. The use of support members 100 on the carriage 26 permits the use of the carriage 26 on steeper sloped roofs than carriages having conventional rollers.

[0039] Although the carriage 26 is shown and described above for dispensing the support sheets 32 and insulation material 36 to form the roof structure 10, as shown in FIGS. 1 and 2, it should be understood that the present invention includes using support members 100 with a carriage, as discussed above, other than the carriage 26 specifically shown in FIGS. 1 and 3. For example, there is illustrated in FIG. 5 an alternate embodiment of a carriage, indicated generally at 150. The carriage is essentially a movable platform, preferably having a deck 152 and a guardrail 154. The movable platform can be used to assist workers on the roof structure, such as by providing a support surface above the purlins or to help protect the workers from falling over the recently completed leading edge of the roof structure. The carriage 150 preferably includes a plate 156 extending from the carriage in an upstream direction which is tucked underneath a leading edge 158 of a recently constructed roof structure 160. The plate 156 preferably substantially closes off any gap between the leading edge 158 of the roof structure and the deck 152. Of course, the carriage 150 may not include the plate 156 and simply be moved closer to the leading edge 158 of the roof structure. The roof structure 160 can be any suitable roof structure, such as for example, a “built-up roof”. A built-up roof is generally formed by first fastening deck sheets 162 on top of the purlins, applying a layer of insulation foam board 164 on top of the deck sheets, and then applying a waterproof membrane 166 over the foam board.

[0040] There is illustrated in FIG. 6, an alternate embodiment of a support member, indicated generally at 200. The support member 200 is particular useful with roof structures not having Z-shaped purlins, as shown in FIG. 4, but with roof beams having a generally planar horizontal upper portion. For example, as shown in FIG. 6, the support member 200 is shown supporting and guiding a carriage on a truss or bar joist, indicated generally at 202. The bar joist has a generally “I” beam shape cross section, and can be formed by fastening two pairs of angled members 204 and 206 onto a bar 208. The bar 208 has a criss cross or wave-like pattern along its length in that it extends in an angled manner and bends at upper and lower portions adjacent the angled members 204 and 206. Of course, the support member 200 will function properly with many different types of bar joist constructions.

[0041] The support member 200 is similar in function and structure as the support member 100 in that it preferably both supports the carriage and helps prevent deformation of the roof members as the carriage travels along the roof structure. The support member 200 includes a roller 210 rotatably mounted on the carriage about an axis which is angled relative to a plane defined by a plurality of parallel spaced apart purlins. The roller 120 has a frustoconically shaped wheel portion 212 similar in structure and function as the wheel portion 128 of the roller 122. The roller 210 also preferably includes a generally frustoconically shaped flange wheel 214 having an outer frustoconical surface 216. An annular recess 218 is formed in the outer surface 216 to define an annular shoulder. The wheel portion 212 and flange wheel 214 can be separate structures or one integral component.

[0042] As shown in FIG. 6, the roller 122 generally conforms to one side of the upper portion or the angled member 204 to trap or confine the upper portion of the bar joist to prevent the bar joist from twisting or rotating out of position. For example, as viewing FIG. 6, the flange wheel 214 prevents the bar joist 202 from twisting or bending in a counter-clockwise direction. It may also be preferred to include two support members 200 disposed on opposite sides of each bar joist to prevent rotation of the bar joist in both directions. For example, the carriage 26 could include a support member 200 in place of roller 30 but oriented on the other side of the bar joist. It should also be noted that the support member 200 can be used with any type of roof beam, such as an eave strut having a C-shaped cross section as described above.

[0043] The support members 100 and 200 can also be pivotally connected to their corresponding mounting assemblies. The pivotal connection provides relatively slight pivotal movement about an axis parallel to the length of the purlins for the support member for discrepancies in the lateral spacing between the purlins. Thus, the pivotal connection allows slight lateral movement while still maintaining support for the carriage.

[0044] The principle and mode of operation of this invention have been described in its preferred embodiments. However, it should be noted that this invention may be practiced otherwise than as specifically illustrated and described without departing from its scope. 

What is claimed is:
 1. An apparatus movable along a roof structure having a plurality of elongated purlins defining longitudinal axes, said apparatus comprising: a carriage movable along the purlins, said carriage extending across the purlins; and a plurality of support members mounted on said carriage and engaged with the purlins, wherein each of said support members includes a flange which abuts one of the purlins to prevent the purlin from twisting about the longitudinal axis of the corresponding purlin.
 2. The apparatus of claim 1, wherein there is at least one support member for substantially every one of the plurality of purlins of the roof structure.
 3. The apparatus of claim 1, wherein one of said support members is mounted within a puller assembly attached to said carriage, said puller assembly engageable to move said carriage along the purlin.
 4. The apparatus of claim 1, wherein said carriage includes a plurality of carriage sections joined together to form said carriage.
 5. The apparatus of claim 1, wherein said support members are removably mounted on said carriage.
 6. The apparatus of claim 1, wherein said plurality of support members each include a roller rotatably engageable with a purlin as the carriage moves along the length of the purlin.
 7. The apparatus of claim 6, wherein said flange is a disc fixed to said roller.
 8. In combination: 1) a roof structure having a plurality of elongated purlins defining longitudinal axes, said plurality of purlins having a generally Z-shaped cross-section including a generally horizontally extending upper portion, a generally horizontally extending lower portion, and a vertically extending web disposed between said upper portion and said lower portion; and 2) an apparatus including: a carriage movable along the purlins, said carriage extending across the plurality of purlins; and a plurality of support members mounted on said carriage and engaged with the purlins, wherein each of said support members includes a flange which abuts said upper portion of a purlin to prevent the corresponding purlin from twisting about its longitudinal axis.
 9. The combination of claim 8, wherein there is at least one support member for substantially every one of the plurality of purlins.
 10. The combination of claim 8, wherein said support members include a roller rotatably engaged with the corresponding purlin as the carriage moves along the length of the purlin.
 11. The combination of claim 10, wherein said flange is a disc fixed to said roller.
 12. The combination of claim 10, wherein said plurality of purlins define a plane, and wherein said roller rotates about an axis at an angle with respect to the plane.
 13. The combination of claim 12, wherein said roller includes a frustoconical surface to rotatably roll along the upper portion of the corresponding purlin.
 14. The combination of claim 13, wherein said upper portions of said plurality of purlins include an upper flange extending at an angle from an edge of said upper portions, and wherein said roller includes a cylindrical surface adjacent said frustoconical surface to rotatably roll along said upper flange of the corresponding purlin.
 15. The combination of claim 14, wherein said flange of said support member has a surface which defines a plane which abuts an edge of said upper flange of a purlin at a perpendicular orientation.
 16. A support member for guiding a carriage movable along a roof structure having a plurality of elongated purlins defining longitudinal axes which are spaced apart from one another in a parallel arrangement, said support member comprising: a mounting member adapted to be attached to the carriage; a roller rotatably attached to said mounting member and adapted to rotatably engage the purlin; and a flange attached to said mounting member and positioned for abutment against the purlin to prevent the purlin from twisting about the longitudinal axis.
 17. The support member of claim 16, wherein said flange is attached to said roller.
 18. The support member of claim 17, wherein said flange is a disc.
 19. The support member of claim 16, wherein said roller includes a frustoconical surface to rotatably engage an upper portion of the purlin.
 20. The support member of claim 19, wherein said roller includes a cylindrical surface adjacent said frustoconical surface to rotatably engage an upper flange of the purlin. 